AND THE OTHER WAY
To those who can’t find the ‘.android_secure’ folder I have found a way to fix the ‘-18 unknown error’ I was getting. After reading the above post to delete the file ‘smdl2tmp1.asec’ I tried it and couldn’t find it. I don’t have any applications installed on the SD card, so I’m guessing this is why I couldn’t find that folder in the SD cards root folder.
So while I had my phone plugged in and the drives mounted, I got the idea to try the install again. And I’m guessing since the SD card was unavailable it couldn’t error out and the install works! Angry Birds is once again wasting my time. I’m guessing you could just unmount the SD card from withen the phone’s software and it should work the same as well. Hope this helps to those who can’t find the folder.